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  • Open Access


    Machining Parameters Optimization of Multi-Pass Face Milling Using a Chaotic Imperialist Competitive Algorithm with an Efficient Constraint-Handling Mechanism

    Yang Yang1, *

    CMES-Computer Modeling in Engineering & Sciences, Vol.116, No.3, pp. 365-389, 2018, DOI: 10.31614/cmes.2018.03847

    Abstract The selection of machining parameters directly affects the production time, quality, cost, and other process performance measures for multi-pass milling. Optimization of machining parameters is of great significance. However, it is a nonlinear constrained optimization problem, which is very difficult to obtain satisfactory solutions by traditional optimization methods. A new optimization technique combined chaotic operator and imperialist competitive algorithm (ICA) is proposed to solve this problem. The ICA simulates the competition between the empires. It is a population-based meta-heuristic algorithm for unconstrained optimization problems. Imperialist development operator based on chaotic sequence is introduced to improve the local search of ICA,… More >

  • Open Access


    Loose Gangues Backfill Body’s Acoustic Emissions Rules During Compaction Test: Based on Solid Backfill Mining

    Junmeng Li1, Yanli Huang1, Wenyue Qi1, Guoqiang Kong1, Tianqi Song1

    CMES-Computer Modeling in Engineering & Sciences, Vol.115, No.1, pp. 85-103, 2018, DOI:10.3970/cmes.2018.115.085

    Abstract In fully mechanized solid backfilling mining (FMSBM), the loose gangues backfill body (LGBB) that filled into the goaf becomes the main body of bearing the overburden load. The deformation resistance of LGBB is critical for controlling overburden movement and surface subsidence. During the process of load bearing, LGBB will experience grain crushing, which has a significant effect on its deformation resistance. Gangues block will be accompanied with obvious acoustic emissions (AE) features in process of slipping, flipping and damaging. Under confined compression test, monitoring the AE parameters of LGBB can reveal the impact mechanism of grain crushing on LGBB deformation.… More >

  • Open Access


    Research on Instability Mechanism and Type of Ore Pillar based on the Fold Catastrophe Theory

    Zhengzheng Cao1, Feng Du2,3,4, Zhenhua Li2, Qinting Wang1, Ping Xu1, Haixiao Lin1

    CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.3, pp. 275-293, 2017, DOI:10.3970/cmes.2017.113.287

    Abstract The stability of ore pillar in mine is essential for the safe and efficient mining. Based on the energy evolvement rule in ore pillar and roadway roof system, the roadway roof and ore pillar are treated as energy release body and energy dissipation body, respectively. Therefore, the double-block mechanical model is established with energy dissipation body and energy release body, and the energy mechanism of ore pillar instability is obtained, based on the fold catastrophe mathematical theory. The research result indicates that the dynamic instability of ore pillar is a physical instability problem caused by the strain softening property of… More >

  • Open Access


    Numerical Simulation of An Experienced Farmer Lifting Tubers of Cassava for Designing A Bionic Harvester

    Wang Yang1,2, Juanjuan Li1, Jian Yang1,3, Lin Wei4

    CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.6, pp. 471-491, 2015, DOI:10.3970/cmes.2015.104.471

    Abstract Harvesting is the most difficult and costly operation in cassava production. Currently, most cassava harvest still depends on manual tools. Effective mechanized harvesters are necessary to improve harvesting quality and reduce production cost. Therefore, it is very important to figure out key information for designing an effective tuber lifting system used in bionic “dig-pull” harvesters. A numerical simulation model of human-stem-tuber-soil system was developed to carry out numerical simulation of manually pulling tuber. Coupling algorithm of Lagrange and smoothed particle hydrodynamics (SPH) was used in the model. Lifting mechanism of experienced farmer was studied at a micro level. Influence of… More >

  • Open Access


    Multiscale Modeling of Collagen Fibril in Bone at Various Crosslink Densities: An Insight into Its Deformation Mechanisms

    S.M. Pradhan1, K.S.Katti1, D.R. Katti1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.2, pp. 181-201, 2014, DOI:10.3970/cmes.2014.098.181

    Abstract Multiscale modeling of collagen fibril is carried out by incorporating the material properties of collagen obtained from steered molecular dynamics into the finite element model of collagen fibril with inclusion of crosslinks. The results indicate that the nonbonded interactions between collagen and mineral contribute to the significant enhancement of the elastic modulus of collagen fibril at all the crosslink densities in both the low strain and high strain regimes. The crosslinks are found to play an important role in the mechanical response of collagen fibril, the enhancement in elastic modulus ranging from 5-11% for various crosslink densities compared to the… More >

  • Open Access


    Hydro-Mechanical Modelling of a Natural Slope Affected by a Multiple Slip Surface Failure Mechanism

    A. Ferrari1, L. Laloui1,2, Ch. Bonnard1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.3, pp. 217-236, 2009, DOI:10.3970/cmes.2009.052.217

    Abstract A coupled hydro-mechanical formulation is presented for the analysis of landslide motion during crisis episodes. The mathematical formulation is used to model a natural slope affected by a multiple slip surface failure mechanism, in which pore water pressure evolution was identified as the main cause for movement accelerations. An elasto-plastic constitutive model is adopted for the behaviour of slip surfaces. Material parameters are obtained by combining the available laboratory tests and the back analysis of some crisis episodes. After being calibrated and validated, the model is applied to improve the understanding of the physical processes involved and to predict the… More >

  • Open Access


    Simulation of the Deformation Mechanisms of Bulk Metallic Glass (BMG) Foam using the Material Point Method

    Jin Ma1, Jay C. Hanan1, Ranga Komanduri1, Hongbing Lu2

    CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.4, pp. 349-384, 2012, DOI:10.3970/cmes.2012.086.349

    Abstract Amorphous metallic foams are an exciting class of materials for an array of high impact absorption applications, the mechanical behavior of which is only beginning to be characterized. To determine mechanical properties, guide processing, and engineer the microstructure for impact absorption, simulation of the mechanical properties is necessary as experimental determination alone can be expensive and time consuming. In this investigation, the material point method (MPM) with C1 continuous shape function is used to simulate the response of a bulk metallic glass (BMG) closed-cell foam (Pd42.5Cu30Ni7.5P20) under compression. The BMG foam was also tested experimentally under compression for validation of… More >

  • Open Access


    Design of Compliant Mechanisms Using Meshless Level Set Methods

    Zhen Luo1, Nong Zhang1, Tao Wu2,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.4, pp. 299-328, 2012, DOI:10.3970/cmes.2012.085.299

    Abstract This paper presents a meshless Galerkin level-set method (MGLSM) for shape and topology optimization of compliant mechanisms of geometrically nonlinear structures. The design boundary of the mechanism is implicitly described as the zero level set of a Lipschitz continuous level set function of higher dimension. The moving least square (MLS) approximation is used to construct the meshless shape functions with the global Galerkin weak-form in terms of a set of arbitrarily distributed nodes. The MLS shape function is first employed to parameterize the level set function via the surface fitting rather than interpolation, and then used to implement the meshless… More >

  • Open Access


    Atomistic Exploration of Deformation Properties of Copper Nanowires with Pre-Existing Defects

    H.F. Zhan, Y.T. Gu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.80, No.1, pp. 23-56, 2011, DOI:10.3970/cmes.2011.080.023

    Abstract Based on the embedded atom method (EAM) and molecular dynamics (MD) method, in this paper, the tensile deformation properties of Cu nanowires (NWs) with different pre-existing defects, including single surface defects, surface bi-defects and single internal defects, are systematically studied. In-depth deformation mechanisms of NWs with pre-existing defects are also explored. It is found that Young's modulus is insensitive to different pre-existing defects, but yield strength shows an obvious decrease. Defects are observed influencing greatly on NWs' tensile deformation mechanisms, and playing a role of dislocation sources. Besides of the traditional deformation process dominated by the nucleation and propagation of… More >

  • Open Access


    Modeling of the Inhibition-Mechanism Triggered by `Smartly' Sensed Interfacial Stress Corrosion and Cracking

    Sudib K. Mishra1, J. K. Paik2, S. N. Atluri1

    CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.1, pp. 67-96, 2009, DOI:10.3970/cmes.2009.050.067

    Abstract We present a simulation based study, by combining several models involving multiple time scales and physical processes, which govern the interfacial stress corrosion cracking (SCC) in grain boundaries, layered composites or bi-materials, and the mechanisms of inhibition using `smart' agents. The inhibiting agents described herein, automatically sense the initiation of damage, migrate to the sites and delay the corrosion kinetics involved in the process. The phenomenon of SCC is simulated using the lattice spring model (for the mechanical stresses), coupled with a finite difference model of diffusing species, causing the dissolution of the interfacial bonds. The dissolution is expressed through… More >

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